[SOLVED] pic output is just 2.5v

[rishad babu]

I had connected the crystal loading capacitors.may be thats not visible in the foto..actualy i have cinnected 22pf capacitors..
Dont compare the schematic with this photograph..i made this breadboard construction just to check if the pic and the program is working properly..led is connected just to see our output..
I need an output of 5v to run the relay..but am getting only 2.5v ,also the program is not working as expected.output becomes 5v when i touch the board.

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J2 pin 2 comes in the schematic i guess..here in this breadboard construction please dont mind about the schematic.
The capacitors i connected across Vdd and Vss are ceramic only.they are 105(1uf)

 

[betwixt]

The "when I touch the board" fix sounds like the reset pin is not at VDD or you have the LVP bit set in CONFIG4L. Try connecting a 10K resistor from pin 38 (PGM) to 0V, if it fixes the problem you have it in LVP mode so either leave the resistor there and lose the pin for other uses or reprogram the PIC with the LVP bit = 0.

Brian.

 

[rishad babu]

LVP mode is OFF in the configuration...there is no change after connecting that resistor to 38 pin..the reset pin is at Vdd.
What should i do with BOR,WDT,CCP2MX,STVREN,ICPRT,MCLRE in the configuration..

 

[K33rg4t3]

Maybe it's a simple problem with your connections, I mean, you didn't put the resistor/other parts legs deep enough into the board?
Take out and put again the parts carefully

 

[rishad babu]

The problem is solved..thank you guys..

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I need a simple high and low voltage cut off circuit

 

[rishad babu]

How can i obtain a 12v output even though the input is less than 12v

 

[betwixt]

Use the logic level to drive a transistor or open-collector logic gate then pull the output up to 12V.

Brian.

 

[FvM]

I notice that the original problem has been solved. Please don't discuss unrelated problems here.

 

[D.A.(Tony)Stewart]

To control a 1HP motor,relay of what ratings should i select...?i mean do i need to consider the starting current also...?the running current would be around 6 or 8A i guess..starting current be around 7 to 10 times,right...?

• Ensure your relay and coil current are properly rated for a 1HP motor and power is routed in tight paired wire or twisted pair.
• Ferrite choke around both contact wires to motor (Common Mode) may be necessary to avoid EMI during switching off.
• Contacts for Inductive loads must be derated 40~60% of resistive current rating for the same life expectancy.
• If the coil current is 75mA for example at 12V, the Transistor base current must be 10% of coil for reliable saturation of switch or Ib=7.5mA, thus Rb=10k is obviously not reliable for switching transistor and coil and will result in premature contact failures for slow operation.
• Reset switch will have contact bounce and the last bounce may not be sufficient duration, therefore add a cap across contacts to ground to make that reliable with RC>= switch bounce time spec, with only an R pullup and C to ground. across contacts.
• If supply drops abruptly on power down, reverse voltage on the 3 terminal regulators may exceed reverse voltage spec, so diodes must be added.

This is just the short list, from a quick read of the schematic.